#include <bits/stdc++.h>
//#include "head.h"
using namespace std;
using ll = long long;

void solve()
{
    ll a, b, n;
    cin >> a >> b >> n;
    ll x = n % (5 * a + 2 * b);
    ll ans = (n / (5 * a + 2 * b)) * 7;
    vector<ll> v(7, 0);
    v[0] = a;
    for (int i = 1; i < 7; i++)
    {
        if (i < 5)
            v[i] += v[i - 1] + a;
        else
            v[i] += v[i - 1] + b;
    }
    ans += lower_bound(v.begin(), v.end(), x) - v.begin() + 1;
    cout << ans;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    while (t--)
    {
        solve();
    }
    return 0;
}